STUDIES IN THE LICHENS OF THE AZORES. PART 2 - LICHENS OF THE

UPPER SLOPES OF PIC0 MOUNTAIN. A COMPARISON BETWEEN THE

LICHEN FLORAS OF THE AZORES, MADEIRA AND THE CANARY ISLANDS

AT HIGH ALTITUDES

O.W. PURVIS, C.W. SMITH & P.W. JAMES

PURVIS, O.W., C.W. SMITH & P.W. JAMES 1994. Studies i n the llchens of the

Azores. Part 3- - Lichens of (he upper slopes of Pico mountain. A comparison

between the lichen tloras of the Azores, Madeira and the Canary Islands at high

altitudes. ArquipPlago. Life and Marine Sciences 12A:35-50. Ponta Delgada.

ISSN 0870-685 1.

Thc lichen flora of the upper slopes of Pico. the major mountain i n thc Azores. is

described betwccn altitudes 1200-2300 m. Two distinct floristic zones arc recognised: an

upper. species poor, zone from 1500-2300 m above the inversion laycr and a iower. more

species diverse. zone from 1200-1500 m dependent on the persistence of the cloud laycr.

49 species are reported. 14 of which are new records for the Azores. including two which

are newly described: Ochroleclzia azorica and Stereocaulon macarotlesirutn. The lichcn

communities above the cloud layer. dominated principally by species of Stereoca~rlot~ and

Placopsis gelida are compared with those of other documented floras of Macaronesian

islands at high elevations. The paucity of species on the upper slopes of Pico is considered

to be primarily the result of the isolation of the Azores. the recent nature of the substrate

and severity of the climatic conditions.

PURVIS, O.W., C.W. SMITH & P.W. JAMES 1994. Estudo dos liquenes dos Aqores.

Parte 2 - Liquenes das encostas de altitude da montanha do Pico. Cornparaqiio

entre as floras de liquenes de altitude das ilhas dos Aqores, Madeira e Canirias.

Arquipe'lago. CiEncias Biol6gicas e Marinhas 12A:35-50. Ponta Delgada. ISSN

0870-685 1.

Dcscreve-se a flora de liquenes das encostas alas do Pico. a maior montanha dos Aqores.

entre os 1200 - 2300 m de altitude. Reconhecem-se duas zonas Iloristicas distintas: uma

clcvada. entre os 1500-2300 m, acima da camada dc invcrsiio. pobre em espicics, c uma

zona baixa. entre os 1200-1500 m. com maior diversidadc espccifica. dcpendente da

pcrsistirncia da faixa de nuvens. Registaram-se 49 csp6cics de liquenes. 14 das quais s50

novas ocorrirncias para os Aqorcs. incluindo duas que se descrcvem dc novo: Ochrol~c/zia

nzorica e Sfereocaulot~ nzacaronesicutn. Compam-sc a comunidade dc liqucncs acima da

hixa dc nuvcns do Pico. dominada principalmcntc por Stereocaulotz c Plncopsis geliclrr.

corn as floras documcntadas dc altitude dc outras ilhas da Macaronisia. Considcra-sc quc

a cscassez dc cspdcies dc liqucncs nas cncostas dc altitudc do Pico C. cm primciro lugar. o

rcsultado do isolamcnto recentc dos Aqorcs. mas tamhCrn da naturcza reccntc do

substracto c das scvcras condiqacs climat6ricas.

 

 

 

 

 

 

    

 

 

 

 

 

 

 

 

 

STUDIES lN THE LICHENS OF THE AZORES. PART 2 - LICHENS OF THE UPPER SLOPES OF PICO MOUNTATN . A COMPARTSON BETWEEN THE LICHEN FLORAS OF THE AZORES, MADEIRA ANO THE CANARY ISLANOS AT HTGH ALTITUDES

O.W. PURVIS, C.W . SMITH & PW. JAMES

PURVIS, O.W ., C.W. SMITH & P.W. JAMES 1994. Studies ln the lichens ar the J\zores. Pari 2 - Lichens or lhe upper slopes ar Pico mountain. A comparison between the lichen floras of lhe Azares, Madeira and the Canary Islands at high altitudes . Arquipélago. Life and Marine Sciences 12A:35-50. Ponta Delgada . ISSN 0870-6851.

The lichen flora of lhe upper slopes of Pico. lhe major mounlain in the Azores. is described belween altiludes 1200-2300 m. Two distincl f10ristic zones are recognised: an upper. species poor, zone 1'rom 1500-2300 m above the inversion layer and a iower. more species di verse. zone fram 1200-1500 m dependent on the persistence of lhe cloud layer. 49 species are reported. 14 of which are new records for the Azores. including two which are newly descrihed: Ochro!echia azorica and Slereocau!(J/l lIlacaronesiculIl. The lichen

communities above the cloud layer. dominated principally by species of SlereocaLllon and Placopsis gelida are compared with those of other documented tloras of Macaronesian islands al high elevations. The paucity of speeies on the upper slopes of Pico is considered to be primarily the result of the isolation of the Azores, the recent nature of the substrate and severity of the climatic conditions.

PURVIS, O.W ., C.W . SMITH & P.W. JAMES 1994. Estudo dos líquenes dos Açores. Parte 2 - Líquenes das encostas de altitude da montanha do Pico. Comparação entre as floras de líquenes de altitude das ilhas dos Açores, Madeira e Canárias. Arquipélago. Ciências Biológicas e Marinhas 12A:35-50. Ponta Delgada. ISSN 0870-6851.

Descreve-se a nora de líquenes das encostas altas do Pico. a maior montanha dos Açores. entre os 1200 - 2300 m de altitude . Reconhecem-se duas zonas f10rísticas distintas: uma elevada. entre os 1500-2300 m, acima da camada de inversão. pobre em espécies. c uma zona baixa, entre os 1200-1500 m. com maior diversidade específica. dependente da persistência da faixa de nuvens. Registaram-se 49 espécies de líquenes. 14 das quais são

novas ocorrências para os Açores. incluíndo duas que se descrevem de novo: Ochrolechia [!~orica e Slereocaulon lIlacaronesicLllIl. Compara-se a comunidade de líquenes ac ima da faixa de nuvens do Pico. dominada principalmente por Slereocaulon e Placopsis gelida. com as floras documentadas de altitude de o utras ilhas da Macaronésia. Considera-se que a eSC;:lssez de espécies de líquenes nas encostas de altitude do Pico é. em primeiro lugar. o resultado do iso la mento recente dos Açores. mas também da natureza recente do substracto e das severas condições climatéricas.

011' Willialll PLlr,lis & Pela Jallles. The Narural Hislory MLlseLlln. Crolllwell Rei.. LOIlLÍolI

SW75BD. - Clij/órd SlIlilh. Bo/{{nv Depor/n/e/1/. Ullivnsily o( HOH'aii (II MW/iJa. 3/90

Moi/e Woy. HUllo/Lllu HI 96822. USA.

35

INTRODUCTION

The lichen flora of the Azores has been relatively

poorly studied and, except for a few papers on the

discovery of particular species, there has been

little attempt to describe the predominant lichen

communities (PUKVIS & JAMES 1993). There are

few published records of lichens collected on the

upper slopes of Pico. However. DEGELICIS ( I94 I )

reported that Dr H. Persson collected Ciotiortitr

pyxiduta, Er-intier-tun ~.riglrrii Tuck. ( a s E. leylatldii (Taylor) Miill. A ) and

Pseudocyplzellal-ia cr-omto in a small crater at c.

1350 m. In addition, Stereocarrlor~ fln~*irrngens

Gyeln. (= S. macar-onesicunz Purvis & P. James.

see below) was reported as occurring from 600-

2000 m. More recently, APTROOT (1989)

recorded Coelocaulorz aculeaturn and Placopsis

gelida from near the summit at 2200 m.

By contrast the lichen floras at higher

elevations in Tenerife (TOPHAM & WALKER

1982) and Madeira (ARVIDSSON & WALL 1985)

are better known. Even so, with the exception of

Las Cariadas del Teide (TOPHAM 1982), no

attempt has been made to describe the

predominant lichen communities specifically

occurring in these areas.

The objective of this paper, the second in this

series, is to list the dominant lichens and describe

the major communities occurring on the upper

slopes of Pico emphasising the. saxicolous and

terricolous communities. An account of the

corticolous lichen flora of the relict scrub forests

at lower altitudes is in preparation.

The study area

Pico is a major island, c. 15 by 45 km, within the

central group of the Azores (Fig. 1). The

principal physical feature of the island, the active

volcano Pico (2351 m), is by far the highest

mountain in the Azores (Fig. 2), none of the

other islands reaching half its height. Its cone

rises abruptly from the sea, the slopes on the

north and east exceeding an angle of 40". The

principal cone terminates in a shallow caldera, c.

3 km wide and 60 m deep, from the centre of

which a secondary cone, symmetrical i n shape,

comprising scoriae and lava, rises over 60 m

above the crater rim. There are signs of

continuing volcanic activity as at the summit the

ground is wiwm in places and there are holes

from which hot vapours issue (TUTIN 1953).

Though the peak often appears concealed by

cloud when viewed from lower altitudes this does

not imply that the summit is cloud-capped. In

fact the upper third of the mountain often rises

well above the main cloud layer and is exposed to

the full impact of the sun. Tradewind-induced,

orographic clouds commonly form at 900 - 1370

rn on the northern slopes with a thinner layer, at

1370 - 1520 m on the southern side creating a

rain shadow effect. Throughout the warmer

months the cloud base tends to ascend during

daylight hours, and the afternoon and evenings

are usually less cloudy than during the early

morning (ANON 1945).

The climate of the Azores is oceanic with

comparatively small seasonal fluctuations in

temperature and rainfall at sea level. Annual

precipitatior! is c. 1054 mm at sea level in Faial

(the adjacent island to Pico) increasing about

16% for every 100 m increase in altitude

(SJOCREN 1978) up to a more-or-less well-

developed inversion layer. However, rainfall is

very low towards the summit above the cloud

layer. The mean high temperatures in the Azores

range between 1523°C at sea level and the

diurnal variation rarely exceeds 7°C (ANON

1945), but it would be much more variable above

the inversion layer. The adiabatic lapse rate is

5°C per I000 m, suggesting a temperature at the

summit of between 3-1 1 "C. Above 1600 m frosts

may occur in any month of the year, though they

are very rare in summer. In the three coldest

months. January to March, frosts occur regularly

above 1860 m, occasionally down to 1200 m and

very rarely as low as 600 m. Snow can persist on

the upper slopes in sheltered, shaded places until

mid summer (TUTIN 1953).

Pico is the most recent island i n the Azores

and evolved 250,000 years ago. The last major

volcanic activity on Pico occurred in 171 8 when

there were large and frequent eruptions on the

MADEIRA a

0:

Lisbon I

SELVAGENS

a CANARUES A

4

Fig. 1. Atlantic islands with Pico enlarged below.

Fig. 2. Pico from air showing characteristic cloud formation around mid flanks and exposed upper cone.

southern side of Pico, especially between S.

Mateus and S. JoHo, and S. Luzia and Bandeiras,

with many lava flows and the building of several

large cinder and scoriae cones. In 1720, a

massive lava flow occurred at SoldZo near Lages

(ANON 1945). The lavas are basaltic and include

much unstable pyroclastic material.

The vegetation above 1200 m falls into two

broad zones. The lower of these two zones

supports the upper remnants of the Juniperion

brevifolii alliance at 1200 m and gives way to a

Calluna vulgaris-Daboecia azorica-Thymus

caespititius zone above 1500 m (SJ~GREN 1973).

This Callunetum is a + open, species-poor

community and grows on steep and rather

unstable slopes of volcanic debris interspersed

with little-weathered and nearly bare lava. Near

the summit Callutm has a creeping, wind-swept

habit and never grows more than a few

centimetres high. The rocks at the summit are in

many places covered with the arctic-alpine

liverwort Gymnomitrium adustum Nees (TUTIN

1953); Aridreaea alpina Hedw. is also present at

its only location in the Azores (E. Dias, pers.

comm.).

MATERIALS AND METHODS

Two of the authors (Purvis and Smith) climbed

the upper slopes of Pico on 4 May 1993 from the

beginning of the trail at 1200 m at Cabec;o das

Cabras on the WNW side of Pico. The trail rises

steeply along the western slope, the path veering

to the south at 2200 m from where the ascent of

the rest of the summit cone was made on the

south side. The lichen vegetation was sampled at

approximately 150 m intervals.

Observations and measurements of lichens

were made following procedures outlined in

PURVIS et al. (1992). A list of lichens recorded is

given (Table 1); author citations follow BRUMMIT

& POWELL (1992) and are presented in full

(Table 1); full author citations are also given for

lichens the first time they are mentioned in the

text but which are not indicated in Table 1.

Higher plant nomenclature follows SJOGREN

(1973, 1984) and that for lichens conforms to RESULTS

recent taxonomic papers. A small number of

crustose species remain to be identified which

will be referred to in future papers. Material is

deposited in BM; some duplicates at University

of Hawaii (HAW) and additional specimens at

the Department of Agricultural Sciences,

University of Azores, Terceira.

Chemical analyses were performed using

standard methods of thin layer chromatography

(CULBERSON 1972, WHITE & JAMES 1985). Two

solvent systems TDA (Toluene : dioxan : acetic

acid; 180:45:5) and G (Toluene : ethyl acetate :

formic acid; 139:83:8) were routinely used.

Lichen flora of the upper cloud zone, 1200-

1500 m

At the beginning of the trail at 1200 m scattered,

stunted remnants of the native forest belonging to

the Juniperion brevifolii alliance (SJOGREN 1973)

exist as an elfin forest up to 2 m tall. Erica

azorica and Calluna vulgaris scrub is dominant

with scattered Juniperus brevifolia, Ilex perado

ssp. azorica as well as a ground flora comprising

several grasses including Deschampsia foliosa,

Table 1

Alphabetical list of lichen species of upper slopes of Pico mountain

1 Amygdalaria pelobotryon (Wahlenb.) Norman 26 Moelleropsis nebulosa (Hoffm.) Gyeln. 2 Baeomyces rufus (Huds.) Rebent. 27 Mycoblastus caesius (Coppins & P. James) Tginsb. 3 Biatora sp. 28 * Ochrolechia azorica Purvis, P. James & Brodo 4 Bryophagus gloeocapsa Nitschke ex Arnold 29 ~armel ia saxatilis (L.) Ach. 5 Buellia sp. 30 Peltigera lactucifolia (With.) Laundon 6 Caloplaca sp. 31 P. melanorhhiza Punis, P. James & Vitik. 7 Cladonia azorica Ahti 32 Placopsis gelida (L.) Lindsay 8 C. cervicornis (Ach.) Flotow 33 Platismatia glauca (L.) Culb. & C. Culb 9 C. diversa Asperges 34 * Porpidia cinereoatra (Ach.) Hertel & Knoph

10 C. merochlorophaea Asah. 35 * P. crustulata (Ach.) Hertel & Knoph 11 C. pyxidata (L.) Hoffm. 36 * P. macrocarpa (DC.) Hertel & Scwab 12 C. stereoclada des Abb. 37 * P. musiva (K&ber) Hertel & Knoph 13 C. subcervicornis (Vainio) Kernst. 38 * P. platycarpoides (Bagl.) Hertel 14 t Coelocaulon aculeatum (Schreber) Link 39 * P. tuberculosa (Srn.) Hertel & Knoph 15 * Epigloea soleiformis Dobbeler 40 3 Pseudocyphellaria crocata (L.) Vainio 16 * Epilichen scabrosus (Ach.) Clem. 41 P. intricata (Del.) Vainio 17 8 Erioderma leylandii (Taylor) Miill. Arg. 42 Rhizocarpon obscuratum (Ach.) Massal. 18 Gyalidea hyalinescens (Nyl.) Vezda 43 Stereocaulon azoreum (Schaerer) Nyl. 19 Gyalideopsis muscicola P. James & Vezda 44 S. Ieucophaeopsis (Nyl.) P. James & Purvis 20 Hypotrachyna endochlora (Leighton) Hale 45 S. r?aacaronesicum Purvis & P. James 21 * Lecanora polytropa (Hoffrn.) Rabenh. 46 * Toninia thiopsora (Nyl.) H. Olivier 22 * Lecidea hypnorum Lib. 47 Trapeliopsisflexuosa (Fr.) Coppins & P. James 23 * Lecidella scabra (Taylor) Hertel & Leuckert 48 Verrucaria cf. papillosa Ach. 24 * Leptogiurn lichenoides (L.) Zahlbr. 49 V. cf.nigrescens Pers. 25 Micarea peliocarpa (Anzi) Coppins & R. Sant.

* = new record for Azores t =recorded by APTROOT (1989). not refound during this survey

3 = recorded by DEGELIUS (1941). not refound during this survey

The numbers refer to the species numbers indicated in Fig. 3.

Holcus lanatus and Anthoxanthum odoratum, the

club-moss Diphasiastrum madeirense (J.H. Wilce) J . Holub and the moss Racomitrium lanuginosum (Hedw.) Brid. Macrolichens are scarce and virtually all epiphytic; Platismaria

glauca and Hypotrachyna endochlora are the

dominant foliose species, whilst Cladonia

azorica is locally frequent on the ground in sheltered areas. Crustose species are also rather

rare, much wood being in fact devoid of lichens, though Mycoblastus caesius and Trapeliopsis

flexuosa are relatively frequent on wood and

Gyalideopsis muscicola widespread on tufts of Hypnum spp. on Erica. Stereocaulon azoreum

and S. macaronesicum are the dominant colonists

of pebbles and small lava outcrops with Placopsis gelida and Gyalideopsis hyalinescens.

At higher elevations (1340 m) the ground flora becomes significantly more sparse than at

the start of the trail: a Calluna vulgaris-

Daboecia azorica heath land with Deschampsia and scattered Erica. The most diverse lichen habitat observed on the trail was associated with

a spatter cone where over half of the species recorded were found (Fig. 3, Table 1). The outside of the cone supported a wide range of

mainly crustose species, including Baeomyces

rufus, Gyalidea hyalinescens, Moelleropsis

nebulosa, Placopsis gelida, Rhizocarpon obscuratum, several species of Porpidia,

Stereocaulon leucophaeopsis and Toninia

thiopsora as well as a few macrolichens: Cladonia species, Peltigera lactucifolia,

Stereocaulon azoreum and S. rnacaronesicum. Within the sheltered interior of the cone, the

infrequent phanerogam Ranunculus cortusifolius

occurs together with an extensive assemblage of lichens, most of which are typical at lower altitudes within the laurisilva and which were not

found elsewhere on the trail, including the macrolichens Cladonia subcervicornis,

Leptogium lichenoides, Peltigera melanorrhiza

and Pseudocyphellaria intricata as well as a range of crustose species including an unidentified species of Buellia, Lecidella scabra,

Porpidia platycarpoides and Verrucaria cf.

papillosa.

Lichen flora above cloud zone, 1500-2300 m

At 1520 m, a CallundIkymus heath with scattered, dwarf Erica clumps but few or no

1 Inversion Layer Upper Boundary P I 1

Fig. 3. Distribution of lichens on upper slopes of Pico.

grasses supported few epiphytes, notably

Platismatia g lauca and Parmelia saxatilis with

an unidentified species of Biatora and fertile

specimens of Ochrolechia azorica. Saxicolous

species present include Amygdalaria

pelobotryon, Baeomyces rufus, Lecanora polytropa, Parmelia saxatilis, Placopsis gelida,

rust-coloured specimens of Porpidia crustulata

as well as Stereocaulon azoreum and S.

macaronesicum.

Above this altitude to the summit, epiphytic

species become extremely rare, though

Ochrolechia azorica was recorded on Calluna up

to 1600 m. The higher plant vegetation also

becomes progressively more sparse, above 1900 m it is reduced to prostrate mats of

CallunwThyrnus with Racomitrium. Daboecia is

rare on the extensive, unstable areas of clinker-

like a'a' lava (Fig. 4). The lichen communities

above this altitude are characterised by an

increasingly stunted assemblage of Stereocaulon species together with the less conspicuous

crustose Amygdalaria pelobottyon, Placopsis

gelida, Porpidia crustulata, and P. tuberculosa.

All these species are confined to the more stable

pahoehoe lava, the clinkery a'a' lava being

virtually devoid of lichens probably the result of

its unstable nature. The muscicolous Bryophagus

gloeocapsa and saxicolous Epilichen scabrosus

were noted in the shelter of a boulder on a single

occasion at 2030 m and several species of

Cladonia, mostly rather poorly developed, are

also confined to this habitat; foliose lichens were

absent. At 2300 m, at least 50% of the rock

surfaces are bare. Here the terricolous Epigloea

soleiformis and Lecidea hypnorum were present

in association with the psoromic acid-containing

strain of Cladonia cewicornis.

DISCUSSION (with a comparison for other

Macaronesian island groups)

There are essentially t hee distinct distributions

*of lichens on the upper slopes of Pico; (1) those

which are confined to below the inversion layer

1 .,. 4. Wind-blasted Thymus .ucspitifius / Daboecia a:orica hcnth near summit of Pico.

(30 taxa represented), (2) those found only above the inversion layer (7 taxa represented); and (3) those occurring over the whole range (12 taxa tepresented) (Fig. 3). The greatest diversity of lichens occurs at lower elevations, particularly at the spatter cone (Fig. 3) where there is the greatest range of habitats including sheltered, moist niches on stable rock surfaces. This area

also lies within the area of frequent cloud cover,

experiences a more consistently humid environment, and is subject to lesser extremes of temperature than above the cloud layer. Several species which are typically epiphytic within the

relict cloud forest below, are here saxicolous,

such as members of the normally foliose Lobarion community, including species of Leptogium, Peltigera and Pseudocyphellaria.

Above this zone the phanerogarnic flora becomes increasingly stunted with a corresponding reduction in lichen diversity and a paucity of

macrolichens, probably as a consequence of the extremely inhospitable environment above the cloud layer. Interestingly, there are very few species from lower elevations that exist above the

inversion layer, a reflection of ecological factors such as low rainfall, exposure to widely different temperatures, and high insolation all of which create an inhospitable environment for lichen growth except, perhaps, in shaded situations. The

lichen flora above the inversion layer towards the summit is extraordinarily poor in species and includes as dominants a small number of crustose and fruticose lichen pioneers having cyanobacterial photobionts in external

cephalodia, viz. Amygdalaria pelobotryon,

Placopsis gelida, Stereocaulon azoreum and S. macaronesicum, as well as the saxicolous Porpidia crustulata and P. tuberculosa;

Epilichen scabrosus and Lecanora polytropa are

rare. Many of these species occur within a fairly broad altitudinal range from above the cloud layer to towards the summit (Fig. 3). Moreover,

this flora shows a close resemblance to that of oceanic mine spoil heaps with abundant scoriae

resulting from the smelting of ore material. The flora above the inversion layer on Pico probably represents a more widely distributed,

cosmopolitan element than the lichen flora occurring below the cloud layer; terricolous species are restricted to sheltered habitats, such as shaded rock crevices and beneath boulders. There is a notable absence of Herteliana taylorii

and Rhizocarpon hochstetteri above the cloud zone. two particularly frequent saxicolous species i n the cloud forest below. The sparse flora

observed above the upper cloud base on Pico contrasts dramatically with similar peaks of other Macaronesian islands e.g. Tenerife and Madeira.

Tenerife, situated near the centre of the Canary

Islands archipelago in the mid-Atlantic, west of

southern Morocco, is dominated by the dormant volcano, Pico del Teide (3718 m high), considerably higher than Pico. It is one of the

younger of the Canary Islands having been formed about 5 million years ago. The top of the cloud base occurs at a higher level than on Pico,

at above 1970 m; the peak itself is often above the upper limit of the north easterly trades. From the caldera, Caiiadas del Teide (2250 m) to the

summit (3550 m), TOPHAM (1982) reports 50 species though additional collections were made by previous authors (PITARD & HARMAND 1912, KLEMENT 1965, FOLLMANN & SANCHEZ-PINTO 1981). However, the summit of the peak of Teide was reported as very poor in species, only

Lecanora polytropa being collected. A contributing factor to this scarcity of lichens might be the deleterious effect of sulphurous gaseous emissions from volcanic fumaroles. At the level of the Teide 'crater' floor, which lies at a similar altitude to that of the summit of Pico, the

lichen cover is often very local in crevices or shehered niches, areas away from surfaces exposed to excessive insolation, persistent drought or wind blast, factors deleterious to most

forms of plant life. Precipitation primarily occurs as snowfall in the winter months and the position of the meltwater and seepage flows is clearly of the greatest importance to the saxicolous flora. Significantly, the most diverse habitats occur on

shaded, north-facing cliffs. Major crustose lichen

genera recorded including brightly coloured

(A carospora, Caloplaca, Candelariella,

Dimelaena, Rhizocarpon (geographicum group)

or pruinose species (Acarospora, Aspicilia,

Buellia), including several macrolichens such as

Lasallia and Umbilicaria, all species with photo-

protective mechanisms to shield photobionts

from excessive levels of illumination.

Madeira is situated about 450 km north of the

Canaries and 600 km west of the coast of

Morocco. The highest mountain, Pico Ruivo,

rcaches 1860 m, significantly lower than Pico but

like Pico having a similar, though less extreme

pattern of an early clear cloudless summit

followed by the development of orographic misty

cloud during late morning between altitudes of

500 and 1300 m. The resulting precipitation

maintains the water flow in the levadas which

are a feature of the upper slopes of Madeira.

Thus, compared with Tenerife, the climate in

Madeira is much more humid and would

therefore be expected to be generally favourable

to lichen colonisation and growth. In fact above

1500 m, a wide range of predominantly crustose

species were reported (e.g. KALB & HAFELLNER

1992) but also several macrolichens including

Hypogymnia tubulosa (Schaerer) Havaas and

Leptogium resupinans Nyl. (ARVIDSSON &

WALL. 1985). Personal observations of the

zuthors along the track from Achada do Teixeira

to Pico Ruivo confirm that, unlike the situation

in the Azores on Pico, Erica (E. arborea) grows

to about 1.5 m tall right to the summit, where the

Lubarion persists at sheltered bases. Species

present include: Leptogium burgessii (L.) Mont.,

Leptochidium albociliatum (Desm.) M. Choisy,

Leptogium corniculatum (Hoffm.) Minks,

Lobaria pulmonaria (L.) Hoffm., L. scrobiculata

(Scop) DC., L. virens (With.) Laundon,

Massalongia carnosa (Dicks.) Korber, Nephroma

laevigatum Ach., Pannaria mediterranea C.

Tav., Parmeliella jamesii S. Ahlner & P.M. Jorg,

Peltigera collina (Ach.) Schrader, P.

membranacea (Ach.) Nyl., Psoroina hypnorum

(Vahls) S. Gray, Polychidium muscicola (Swartz)

Gray and Pseudocyphellaria crocata (L.) Vainio.

The tree canopy is dominated by Hypogymnia

maderensis (Tav.) Hawksw., Platismatia glauca

(L.) Culb. & C. Culb. and Pseudevernia

furfuracea (L.) Zopf with occasional Alectoria

sarmentosa (Ach.) Ach., Hypogymnia tubulosa

(Schaerer) Havaas, Lethariella canariensis

(Ach.) Krog, Ochrolechia androgyna (Hoffm.)

Arnold and 0 . szatalaensis Vers. Conditions

here appear to f av~ur growth of lichens over

mosses. A further factor influencing the

composition of lichen communities within the

cloud zone is that of grazing. On Pico Ruivo the

ground flora has few or no grasses whereas on

Pico they are an important component up to c.

1340 m, including several introduced species for

cattle grazing. Burning, selective scrub clearance

and disturbance from grazing have had a

dramatic impact on the vegetation of Pico with a

reduction in the number of shrubs and

consequent decrease in the availabilty of

substrates for lichens, or else terricolous lichens

may become smothered by invasive grasses. An

analagous situation was observed by one of us

(Smith) in- Hawaii Volcanoes National Park

where scrubland at c. 1200 m had 20 years ago

an almost continuous groundcover of Cladina

skottsbergii, Stereocaulon ramulosum and a

species of Stereocaulon attributed to S. vulcani.

Following the introduction of the alien grass

Andropogon virginicus, lichens were unable to

compete and virtually disappeared. However,

neither burning nor clearance of elfin scrub

appears to have been carried out at higher levels

(above 1500 m) on Pico as this area has little or

no agricultural value. Towards the summit of

Pico Ruivo, poorly vegetated areas on clinker-

like pyroclastics are much more reminiscent of

those on the higher slopes of Pico and support far

fewer lichen species, including Epilichen

scabrosus (Ach.) Clem., Placopsis gelida in

many forms, Stereocaulon vesuvianum Pers., S.

leucophaeopsis (Nyl.) P. James & Purvis,

Trapelia involuta (Taylor) Hertel and

Trapeliopsis wallrothii (Horke ex Sprengel)

Hertel & G. Schneider, contrasting sharply with

the the smoother, stable andesitic formations

more frequent at slightly lower levels which

support a far more diverse lichen flora which

merits closer examination.

Explanations for the differences in the

composition of the lichen floras seen on the mountain summits of these Atlantic islands may be due to one, or more probably, a combination

of factors. These include: climatic, in which fluctuations in temperature and the amount and persistence of moisture regimes are important;

the degree of exposure and presence of shelter, e.g. shrub cover; variations in niche structure; the physical and chemical nature of the substrate;

the distance from nearest land masses acting as sources for inoculation either through wind or dispersal by birds along migratory routes; and their age and the last period and intensity of

volcanic activity which could result in the local

extinction of particular species or the local deleterious effect of volcanic gases.

Concerning climate, in view of the more

southerly location of Madeira and the Canaries and their proximity to the African mainland, it

might be expected that their climate would be

significantly warmer than the Azores. However, the Azores are on the southern edge of the warm North Atlantic Drift, Madeira is at the

commencement of, and the Canaries within, the south-westward drift of the Canary current. Thus,

in spite of lying some 600 miles to the south, the '

temperature of the surface water of the western Canary Islands is similar to that in the Azores

and that of the eastern Canaries is cooler mainly due to the upwelling of cold water that occurs off the African coast between Tangier and Cape Verde. Thus the surface waters of the Azores is

usually 3 to 5' warmer than the average of the ocean in these latitudes, while that of the Canaries is between 2 and 4" colder than the average warmth of' surface waters at these latitudes.

The only notable continental influence on the climate of the three island groups is the hot, dry

dusty weather that often accompanies easterly and south-easterly winds. This influence is strongest in the Canaries when dry easterly winds may bring dust from Africa during all seasons of the year. It has weakest impact in the Azores, but in Madeira dry easterly winds occasionally occur between July and September. However, very little

dust, if any, falls on the peak of Tenerife at

heights above 2730 m. Pico del Teide is often

above the upper limit of the north easterly trades and a definite westerly current is common at heights exceeding 2420 to 2730 m. The Azores, situated in the mid-Atlantic (Fig. 1) with dominantly westerly winds is also not on major

bird migratory routes. The chances of air-borne lichen propagules arriving on Pico must therefore

be smaller than on similar mountains in Tenerife and Madeira. Furthermore, in view of its younger age there has been less time for colonisation.

It is probable therefore that a combination of

factors, including variation in niche diversity, particularly in relation to the type and stability of

rocks as well as the predominant wind patterns and the closer proximity of Teneriffe and Madeira to the north-west African coast might

explain the richer diversity of lichens observed above the cloud layer on these islands as compared with the lower diversity in the Azores.

However, the lichen flora of the north-west African coast is relatively poorly documented making such comparisons difficult. In the case of

Madeira the more humid climate at upper altitudes must also play an important role in

enabling the colonisation and growth of a greater range of species. However, it is to be expected

that a more intensive study of high ground on Pico would reveal further species, particularly on the more stable surfaces of cliffs beneath the summit cone, though access is here difficult. A fuller analysis of the lichen floras, including a detailed study of primary (sexually reproducing) and secondary (asexually reproducing) species, occurring in a wider range of habitats on these and other islands will be necessaty to establish their relationships and possible origins.

ACKNOWLEDGEMENTS

O.W. Purvis and P.W. James gratefully acknowledge

receipt of a grant from Professor C.W. Smith (University of Hawaii). Dr H.R. Martins (University of Azores) is thanked for most generous logistical support and advice. Dr D.J. Galloway (Natural History

Museum) is thanked for his helpful discussions.

APPENDIX

Ochrolechia azorica Purvis, P. James & Brodo

Thalius tenuis vel sat crassus, albus vel cinereus;

soralia granulata, dispersa, discreta, interdum

irregularia, 0.3-0.8 mm in diam.; apothecia 0.5-

1 (- 1.5) mrn diam., discis dilute luteo-aurantiacis

vel testaceis, epruinosis vel leviter pruinosis,

marginibus aequatis, laevibus haud

prominentibus, thecio 200-230 pm alto,

hypothecio c. 130 pm crasso, strato algaro infra

hypothecium continuo, cortice plerumque

distincto, radiato; ascosporae 55-70(-75) x 25-3 1

pm. Thallus acidum variolaricum continens,

apothecia acidum variolaricum et gyrophoricum

continentia.

Typus: Azores: Pico, NW slopes of Pico, c. 3 km

S. of road EN3, through Cerrado de Sonicas, S.

of track leading to aerial, alt. 1000-1 150 m [site

241, 1 1 April 1992, O.W. Purvis & P. James (BM

- holotypus) (Fig. 5).

Thallus thin to moderately thick, -e

continuous, smooth, only irregularly fissured

through cracking of underlying substrate,

membranous, white to grey-white, spreading,

often encircling twigs and small branches;

prothallus absent or inconspicuous, white,

sorediate. Soralia c. 0.3-0.8 mm diam., scattered

and widely dispersed, rarely 2- to 3-confluent,

rounded, excavate, appearing ulcerose with a + ragged rim, sometimes becoming erumpent,

convex-efflorescent, concolorous with thallus or

pale yellow-grey; soredia k coarsely granular,

0.1-0.15 mm diam. Apothecia 0.5: I(-1.5) mm

diam., occasional, mostly discrete and widely

dispersed, rarely 2- to 3-contiguous, sessile

throughout; disc pale yellow-orange or flesh-

coloured, smooth to + scabrid, 2 translucent, not

or very sparingly white-pruinose, concave at first

becoming + plane; margin persistent, thick,

smooth, k tumid, even or occasionally angular

through mutual pressure. Pycnidia rare, 0.2-0.4

mm diam., low-conical with a flattened apex.

Photobiont cells green, 9-10 ym diam.,

forming a distinct and continuous algal layer, 20-

50 pm tall beneath hypothecium with scattered,

subcontinuous radiating clumps in the outer

margin just proximal to a rather well-developed

cortical region; photobiont layer, thalline margin

and medulla densely granular, granules

dissolving in K. Thecium 200-230 pm tall, 2

colourless, pale grey-brown, semi-opaque and

densely granular for upper ca. 90 pm, partly

dissolving in K leaving a thin layer of crystals ca.

10-15 pm below upper edge (surface of disc),

non-granular below, paraphyses densely

branched and anastomosed. Hypothecium ca. 130

pm thick, pale yellow-brown, 2 unchanged in K,

granular inclusions absent. Asci cylindrical-

clavate, (1)2- to 4-spored, uniformly thin-walled.

Ascospores 55-70 (-75) x 25-31 p, ellipsoid,

ovoid or rarely + weakly reniform, colourless,

simple, wall uniformly thin, 1.5-2 pm thick.

Conidia bacilliform, 4.5-5.5 x I pm.

Chemistry: apothecial and thallus cortex and

soralia K-, C+ yellow, KC+ yellow; apothecial

disc K-, C+ red, KC+ red, Pd-. Contains

variolaric acid in the apothecial and thallus

cortex and soralia, variolaric and gyrophoric

acids (with a trace of lecanoric acid) in the

apothecial disc, and lichesterinic and

protolichesterinic acids in the thallus and/or

apothecia.

Apparently restricted to decorticated wood

above an altitude of c. 1000 m on Pico where it

occurs principally on Erica azorica in the

uppermost zone of the Juniperion brevifolli

alliance and at higher elevations (to at least 1600

m) on dead stems of Calluna vulgaris in the

Callunetum in very exposed situations.

Associated species present include: Cladonia

azorica, (crustose primary thallus), Lecanora

farinaria Borrer, L. aff. strobilina (Sprengel)

Kieffer, L. symmicta (Ach.) Ach. agg.,

bxospora elatina (Ach.) Massal., Micarea

peliocarpa (Anzi) Coppins & R. Sant.,

Mycoblastus fucatus (Stirton) Zahlbr. (= M.

sterilis Coppins & P. James, Parmelia saxatilis,

Pertusaria pulvinata Erichsen, Sphaerophorus

globosus (Huds.) Vainio, Thelotrema lepadinurn

Fig. 5. Ochrolechia azorica (part of holotype). Scale in mm.

(Ach.) Ach. and Trapeliopsis flexuosa.. (Fr.) Coppins & P. James.

Ochrolechia azorica is characterised by the

small, scattered, punctifonn, ulcerose, mrginate soralia containing granular soredia; the soralia

resembling those of Caloplaca ulcerosa Coppins & P. James and C. obscurella (Lahm ex Korber) Th. Fr. The thin, even, smooth, white thallus, margins of 'the sessile apothecia and soralia contain variolaric acid (C+ yellow); in addition the disc contains gyrophoric acid (C+ red). In longitudinal section the apothecia have a distinct and continuous photobiont layer below the

hypothecium with scattered, somewhat radiately arranged photobiont clusters in the outer

apothecial margin proximal to a well-developed

cortical region. In this arrangement of the photobiont 0. azorica resembles certain species in the 0. tartarea aggregate, e.g. 0.

subpallescens Vers., as well as some in the 0.

parella aggregate e.g. 0. pseudopallescens Brodo, and so this character alone can be used

definitively assign 0. azorica to one or the other

group. In the 0. tartarea group, the apothecial margin disc is characteristically smooth, as is

that of 0. azorica, but variolaric acid is only usually present in traces and the thallus is almost

always C+ red (gyrophoric acid or one of the hiascic complex of acids). Variolaric acid is a major constituent of the 0. parella and 0. upsaliensis groups but species in these complexes have notably scabrose and densely white- pruinose apothecial discs. 0. alboflavescens (Wulf.) Zahlbr. in the 0. parella group has rounded, well-delimited soralia, but has larger apothecia with pruinose-scabrid discs and a more uneven, darker coloured thallus. In the 0.

upsaliensis group, the apothecial discs are notably scabrose and devoid of gyrophoric acid. The key to placing 0. azorica must therefore rest on the fatty acid chemistry. In containing both

protolichesterinic and lichesterininc acids, our new species has the same chemosyndrome as

several members of the 0. parella group (e.g. 0.

pseudopallescens and 0 . alboflavescens) unlike

any species in the 0 . tartarea or 0 . upsaliensis

groups (BRODO 1991), and we can therefore

confidently relate it to that complex.

0. azorica appears to be endemic to the

Azores, possibly restricted to Pico as this is the

only island where the mountains exceed 1000 m.

A similar species chemically, 0. szatalaensis

Vers., which also contains variolaric, but lacks

gyrophoric, acid in the apothecia, has recently

been observed by the authors on Erica arborea

on high ground in Madeira on Pico Ruivo. 0.

szatalaensis further differs from 0. azorica in

lacking soralia and has densely white-pruinose

apothecial discs and is so far unknown in the

Azores, though is also present in the Canary Is.

(BM).

BRODO (1991) draws attention to the fact that

very few temperate corticolous species of

Ochrolechia are widespread. Of approximately

31 species described, only 4 % are definitely

known to occur in both Europe and North

America. This is all the more surprising in view

of the large number of species with asexual

propagules. It would seem likely therefore, that

recent speciation is relatively rapid in this genus

as also in e.g. Menegazzia, and it is not

inconceivable that 0. azorica is restricted to

Pico, particularly in view of its specialised

habitat and the relatively remote location of the

Azores. However, in view of our incomplete

knowledge of the distributions of crustose lichens

on atlantic islands, further study will be

necessary to fully test this hypothesis.

Additional species of 0. azorica examined:

Pico: 11 km SE of Madalena, 1-1.5 km S. of road

EN-3, Cerrado de Sonicas, cloud forest within

sheltered gully and alongside deep craters, alt.

1100 m, 25 April 1993 [site 461, O.W. Purvis &

P.W. James; along Pico trail to summit from

Cabeqo das Cabras on western side of Pico, alt.

1520 m, 4 May 1993 [site 651, O.W. Purvis &

C.W. Smith; Along Pico trail to summit from

Cabeqo das Cabras on western side of Pico, alt.

1600 m, 4 May 1993 [site 651, O.W. Purvis &

C.W. Smith.

Stereocaulon macaronesicurn Purvis & P. James

Typus. Pico: as S. flavireagens Gyeln. 600-1500

m, 7 May 1937, Herman Persson, det. Gunnar

Degelius. (UPS-holotypus) (Fig. 6).

Stereocaulo vesuviano sirnilis, sed

phyllocladia centris non-fuscis et acidae

lichenosae dissirnile.

Pseudopodetia forming dense tufts, 5-lo(-20)

cm across, firmly attached to rock substratum, to

3 cm tall, erect or + decumbent, robust, + terete

or somewhat flattened, simple or sparingly

branched above, apices + flexuose, grey or

pinkish grey-white, ecorticate, without

tomentum, surface * coarsely striate or ridged.

Phyllocladia coarsely nodular-granular, 0.3-0.8

mm diam., sparse or crowded, often in scattered,

convex, individually rounded, glomerule-like

clusters or becoming confluent, + uniformly

white-grey, lacking individual dark centres with

a paler rim. Cephalodia apparently absent,

though loosely associated, black, irregular tufts of

Stigonema occasionally present intermingled

between phyllocladia. Apothecia rare, 0.3-0.8

mm diam., pale to dark brown, convex, lateral,

sessile, mainly attached towards apices of main

branches; epithecium brown, thecium 45-60 pm

tall, colourless; paraphyses mostly simple, apices

sometimes with a dark brown cap; hypothecium

pale yellow-brown; asci 8-spored. Ascospores

(27-)35-45(-60) x 3-4 ym, narrowly fusiform,

often attenuated towards one end, colourless,

(1-)3-4 (-5) - septate.

Thallus K+ yellow-red, Pd + red, C-

(norstictic and connorstictic acids and two

unidentified compounds (rf 3 in TDA and G, red-

orange and brown-yellow, Fig. 7). Stereocaulon macaronesicurn is characterised

by the combination of its unique chemistry and

form and disposition of the phyllocladia;

morphologically it resembles S. vesuvianum but

lacks the characteristic dark centres of the

phyllocladia of that species. The pseudopodetia

in fresh material are also more obviously tinged

pinkish, contrasting with the phyllocladia which

are starkly white-grey changing to a dull grey in

the herbarium.

Fig. 6. Stereocaulon ~ a r o n e s i c m (part of holotype). Scale in mm.

Morphs In exposed situations, such as on boulders, above the adiabatic zone, form more adpressed, compacted tufts, to 2 cm tall, with more . decumbent and richly -branched pseudopodetia; the phyllocladia aremore densely crowded, becoming flattened and shield-like, often coalescing and forming a & continuous

cracked crust over the surface of the pseudopodetium, curving upwaxdly at the

margins. Such Azorean specimens were previously referred to as S. vuEmi f. mauwe-

loae (Magn.) Lamb (holotype of S. muna-ioae

Magnusson - Hawaii, Mauna Lda, above the rest house, alt. 3400 m, 14 November 1922, C. Skottsberg 1723, WPSI), a habitat form later considered by ((1977) to be comparable with f. um&ona~nz (WaIlr.) Lamb of S.

vesuvianm var. nodulosmt (Wallr.) Lamb. However, as intermediates may be found amongst

the Azorean specimens of S, macaronesicurn, no formal taxonomic distinction is made here of the stunted material which is here considered as an ecotype.

The Azorean collections of Herman Persson that we consider as S. macamazesicum, were labelled by Magnusson and Degelius as S. flavireagens Gyeln. (isotype - Hawaii, Glenwood,

On lava, alt. 1200 m, E, Schnell, UPS!). It should be noted, however, that Magnusson obviously had some doubts about his naming of these collections as he originally ascribed the name of 3. oceanicm' to some of the specimens,

though this name was never formally validated. Notwithstanding, L~PMB (1977) considered this Azorean material to be referable to S. vuicani (Bory) Ach. (RBunion island - holotype PC- Thuret!; isotype UPS E ) in which he also included S. fZavireagefis (Lamb 1977) and its two forms, S. flavireagens f. cinerascens Magmsson (holotype - Hawaii, E. Maui, Hateakala, along Hdemau trail, 5 August 1938, 0. Selling, UPS!) and f. densum Magnusson (Hawaii, top of

Hualalai, alt. 2600 m, 25 November 1922, C. Skottsberg, 1569, UPS!), as synonyms. Thus, in

using the name S. vulcaai, Lamb allies the Azorean material with that from Hawaii and

RCunion island. Our examination of the type

material of S. jlavireagens from Hawaii

including its forms cinerascens and densum as

well as that of S. maunae-loae (type cited above),

although mostly in a poor and fragmented

condition and morphologically rather similar to

S. macaronesicum, shows that this Hawaiian

material has a simpler chemistry of atranorin,

norstictic and connorstictic acids only.

Furthermore, the type material of S. vulcani,

unlike S rnacaronesicum and S. jlavireagens, has

phyllocladia with conspicuously darkened centres

surrounded by a paler rim and a chemistry

besides atranorin, of norstictic acid (trace), stictic

acid and a suite of accessory substances,

including menegazziaic acid, features suggesting

that the type material of S. vulcani is, in fact,

closely related to the S. vesuvianum agg.

Unfortunately, only immature apothecia are

present in type material examined, though their

lateral, more-or-less sessile position towards the

tips of the podetia further suggests that S. vulcani

may be referable to S. vesuvianum s.str. The

above observations confirm that S.

rnacaronesicum is therefore a Macaronesian

species so far only known in the Azores (all main

islands) and in the Canary Islands (Tenerife) and

furthermore that the Hawaiian material which

has been named as S. vulcani or S. jlavireagens

is not the same as S. macaronesicum.

There is a second Macaronesian endemic

Stereocaulon in the Azores: S. azoreum

(Schaerer) Nyl. which has finely granular

phyllocladia and elegant, richly branched, often

richly fertile pseudopodetia with terminal

apothecia; it is unique amongst species of

Stereocaulon in containing both lobaric and

stictic acids. A further species, S. atlanticum (Lamb) Lamb (= S. meyeri Stein ssp.

atlanticum), described from the Azores (S.

Jorge), has smooth pseudopodetia with terminal,

capitate soralia, shortly stalked, sacculate

cephalodia and contains stictic acid, norstictic

acid and atranorin as well as accessory substances of the stictic acid complex; this

species has also been recorded from central and

South Africa as well as tropical America and

Pro

C o n n S 0

0 Sti

0 Cons

Fig. 7. TLC chromatogram run in solvent G. 1 = control, 2 = S. macaronesicum (holotype) and 3 = Stereocaulon vesuvianum. Atr = atranorin, Corn = connorstictic acid, Cons = constictic acid, Pro = protocetraric acid, Sti = stictic acid, Usn = usnic acid, A = red-orange and B = brown-yellow unidentified substances.

belongs to subsect. Aciculisporae which includes

the widespread species, S. ramulosum (Sw.)

Rausch.

Additonal specimens examined: Azores: - Faial: Praia do Norte (on lava, covering large

patches), 8 July 1928, O.C. Schmidt [as S.

flavireagens f. cinerascens] (UPS); 3 May 1997,

Herman Persson [as S. jlavireagens Gyeln.]

(UPS). - Pico: Along Pico trail to summit from

Cabeso das Cabras on western side of Pico, alt.

1200-1960 m, 4 May 1993 [site 651, O.W. Purvis

& C.W. Smith (several specimens-BM); liten

crater, c. 1350 m, Herman Persson [as S.

flavireagens Gyeln., redet. S. vulcani var.

maunae-loae (H. Magn.) Lamb] (UPS); Toppen,

9 May 1937, Herman Persson [as S. flavireagens]

(UPS). - St Jorge: between Calheta and Topo, 15

May 1937, Herman Persson [as S. jlavireagens,

redet. S. vulcani] (UPS). - Terceira: Terra do

Moriiio, 19 April 1937, Herman Persson [as S.

flavireagens Gyeln., redet. S. flavireagens f.

cinerascens by Lamb] (UPS); Terra do Moriiio,

19 April 1937, Herman Persson [as S.

flavireagens Gyeln., redet. S. vulcani (Bory)

Ach. by Lamb] (UPS). Canary Islands: Tenerife,

Hartung, between basaltic rocks, Hepp Flechten

Europa 2, pro parte with S. vesuvianum [No.

652. Lich. Helvet. em . Schaer. et Hepp, as 2. S.

denudatum I3 vesuvianum. (UPS, BM)].

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